To an optical receiver such as an optical receiving device for coherent communication, an optical signal with multiplexed polarization or phases is input via a polarization holding fiber, and the optical signal is split depending on polarization by a polarization beam splitter (PBS). The split optical signal is separated depending on phases, for example, by a 90-degree optical hybrid device. The separated optical signals are converted into electric signals by light receiving elements. For example, Japanese Patent Laid-Open No. 5-158096 discloses a technique in which an optical coupler as the 90-degree optical hybrid device is used in an optical receiving device for coherent communication.